We report a case of dedifferentiated chondrosarcoma of the chest wall. After resection, the chest wall defect was reconstructed using polypropylene mesh and a transverse rectus abdominis myocutaneous flap. A 61-year-old woman presented with a 16-year history of a slow-growing mass underneath the right chest wall. After percutaneous biopsy, preoperative cytopathological examination of the large mass revealed dedifferentiated chondrosarcoma. The tumor was resected with a wide margin along with the chest wall including skin, the right seventh to tenth ribs, and part of the diaphragm. The chest wall defect was reconstructed with a polypropylene (Marlex) mesh sheet followed by a left-side transverse rectus abdominis myocutaneous flap.